This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A143720 #7 Jan 29 2025 22:12:00 %S A143720 8,9,16,18,25,27,32,40,45,49,50,54,56,60,63,64,75,80,81,84,88,90,96, %T A143720 98,99,104,108,112,117,120,121,125,126,128,132,135,136,140,147,150, %U A143720 152,153,156,160,162,168,169,171,175,176,180,184,189,192,198,200,204,207,208,216 %N A143720 Complement of A143719. %H A143720 Robert Israel, <a href="/A143720/b143720.txt">Table of n, a(n) for n = 1..10000</a> %p A143720 filter:= proc(n) local F,M; %p A143720 F:= ifactors(n)[2]; %p A143720 M:= max(F[..,2]); %p A143720 ormap(proc(q) local e; padic:-ordp(n,q) < add(floor(log[q](e+1)),e=F[..,2]) end proc, select(isprime, [$2..M])) %p A143720 end proc: %p A143720 select(filter, [$2..300]); # _Robert Israel_, Jan 29 2025 %Y A143720 Cf. A143719, A141586. %K A143720 nonn %O A143720 1,1 %A A143720 _N. J. A. Sloane_, Nov 29 2008